Easy-open container



R. W. MURDOCK EASY-OPEN CONTAINER Sept. 5, 1967 2 Sheets-Sheet 1 FiledSept. 29, 1965 w M 0 Q I i 4 w INVENTOR. HJBBHT HZ Mmzzmazc p 1967 R. w.MURDOCK 3,339,790

EASY-OPEN CONTAINER Filed Sept. 29, 1965 2 Sheets-Sheet f3.

' INVENTOR: B05532" W MUHUUUK.

United States Patent M 3,339,790 EASY-OPEN CONTAINER Robert W. Murdock,Vermilion, Ohio, assignor to Gregory Industries, Inc., Lorain, Ohio, :1corporation of Michigan Filed Sept. 29, 1965, Ser. No. 491,154 8 Claims.(Cl. 220-54) This invention relates to lids for containers such as tincans and more particularly to such lids with opening tabs weldedthereto.

Containers, particularly cans for food and drink, frequently are nowmade with tabs affixed thereto by means of which the cans are opened byhand without the requirement of a can opener. Heretofore, the tab hascommonly been afiixed to the lid by forming a hole in the tab and byforming an upwardly-extending projection on the lid. The projection wasthen inserted through the opening and peened over to rivet the tab tothe lid, the rivet being a structurally integral part of the lid. Thistechnique of affixing the tab has had several disadvantages. The methodof attachment has been relatively slow and has been limited to the useof certain metals, particularly aluminum, for the can lid, since themetal has had to be highly ductile in order for the rivet projection tobe formed therein. Furthermore, the can lids have been somewhatdifiicult to open with this type of tab because, as will be moreapparent later, the tab has had to be located centrally with respect toa starting end of the opening strip scored in the top of the can. Thismeant that a large part of the scored line separated all at once as thetab was lifted, requiring considerable extra force for the initialopening step.

The present invention provides a new lid and opening tab in which thetab is welded to the lid to enable the tab to be attached rapidly andinexpensively. The lid also can be made of other metal than aluminumsince the ductility of the metal is not important. Further, with the newtab and the welding technique, the tab can be attached to the lid in anofi-center position adjacent the score line thereon so that only a smallportion of the score line is initially parted, requiring a minimum offorce.

It is, therefore, a principal object of the invention to provide amethod for attaching an opening tab to a can lid more rapidly andinexpensively than heretofore.

Another object of the invention is to provide an attachment for anopening tab and can lid which does not require that the lid be made ofsoft, ductile metal.

Still another object of the invention is to provide a can lid with anopening tab affixed thereto in a position which enables the lid to beopened with much less force than heretofore required.

Numerous other objects and advantages of the invention will be apparentfrom the following detailed description of a preferred embodimentthereof, reference being made to the accompanying drawings, in which:

FIG. 1 is a plan view of a scored can lid, prior to being assembled witha can, and an opening tab afiixed to the lid in accordance with theinvention;

FIG. 2 is a somewhat enlarged view in transverse cross section takenalong the line 22 of FIG. 1;

FIG. 3 is a further enlarged view in vertical cross section taken alongthe line 3-3 of FIG. 2;

FIG. 4 is a greatly enlarged, fragmentary view of a portion of the lidand a portion of the opening tab, showing the position of attachment ofthe tab to the lid;

FIG. 5 is a fragmentary view in vertical cross section similar to FIG. 2but showing the opening taband lid in a partly opened position;

FIG. 6 is a fragmentary plan view of the can lid with the tab pulledfarther than in FIG. 5 to open the lid further;

3,330,790 Patented Sept. 5, 1967 FIG. 7 is a partly schematic view inperspective apparatus for afiixing the tab to the lid;

FIG. 8 is a view in vertical cross section of a welding tool of theapparatus shown in FIG. 7;

FIG. 9 is a view in perspective of a chuck of the welding tool; and

FIG. 10 is a wiring diagram of an electrical source and controls for thewelding tool.

As shown in FIGS. 1-6, a can lid capable of being opened without a canopener is indicated at 10 and includes a rim 12 by means of .which thelid can be connected to a can body 14- in a conventional manner, asshown in FIG. 2. The manner in which the lid is connected to the body isnot part of the invention and the rim 12 can be of the usual design,although preferably being slightly higher. The lid 10 has an openingstrip 16 of spiral configuration, in this instance, which includes aterminal portion 18, a peripheral portion 20 adjacent the rim 12, and aninwardly-extending starting portion 22 terminating in a roundedinitiating or leading edge 24. The opening strip 16 is defined by ascore line 26 which extends partly through the thickness of the metal ofthe lid 10 to enable it to be more easily separated. A reinforcing rib28 also is of spiral configuration and lies adjacent the opening strip16, separating it from a central portion 30 of the lid. The reinforcingrib 28 stiifens the central portion 30 and reduces its tendency to bendas the strip is pulled and bent outwardly.

An opening tab 32 is affixed to the lid 10 by being welded to theinwardly-extending portion 22 near the edge 24, as will be discussed indetail subsequently. In the specific form shown, the tab 32 is of sheetmetal from 0.011 to 0.017 inch in thickness and preferably from 0.012 to0.015 inch. It has been found that thinner stock will bend too easilywhen the lid is opened and possibly even burn through at the weld,whereas thicker stock is unnecessary and increases the overall cost ofthe lid. As shown particularly in FIG. 1, the tab 32 has a squared freeend 34 and a tapered fastened end 36 terminating in a short edge 38. Thelength of the short edge 38 preferably is substantially no greater .thanthe width of the inwardly-extending portion 22 of the strip 16, overwhich the edge 38 of the tab is positioned. Particularly, the end 36 istapered to space the edge 38 from the reinforcing rib 28, eliminatingthe corner which might otherwise contact or almost contact the rib 28and cause arcing therebetween rather than at the desired point ofattachment.

Reinforcing ridges 40 extend longitudinally of the tab 32 near sideedges 42 and should extend at least to positions transverse to a portionof an attaching dimple or projection 44 to prevent bending of the tab asit is pulled upwardly. The dimple 44 is located at the tapered end 36 ofthe tab 32 between the ridges 40 and near the short edge 38. The dimple44 preferably is spaced slightly from the short edge 38 but can betangential thereto or even intersect the edge slightly. The size of thedimple 44 is very important. As shown, the dimple or projection isgenerally arcuate in vertical cross section taken longitudinally of thetab and has a radius of from three-thirtyseconds inch to one-fourthinch. The dimple 44 also should extend downwardly below the plane of themain handle portion of the tab a distance of from one-thirtysecond inchto one-fourth inch. The bottom of the dimple 44 can be slightlyflattened if desired to provide a slightly broader base for the weld.The base should not be too large, however, since the larger sizeincreases the area of attachment of the dimple to the lid and increasesthe chance for this area to incorrectly bridge the score line formingthe leading edge 24. It is even more important that the dimple shouldnot be too small in diameter or too sharp at the base since this willconcentrate the weld current excessively and-cause the lid 10 to beburned through at the point of attachment or at least destroy theprotective coating on the metal at the lower surface thereof, therebyleaving the lid susceptible to attack by the contents of the can.

The dimple 44 preferably is attached to the inwardlyextending portion 22of the strip at a small shaded area 46, as shown in FIG. 4. The area ofattachment preferably is located adjacent the leading edge 24 and isoutof-center or eccentric with respect to the geometric center of theedge 24, so as to be much closer to one portion of the edge than otherportions. This is accomplished by locating the area 46 between thecenter of curvature designated C and the leading edge 24, with the areabeing preferably closer to the edge than the center C, but not so close,of course, as to overlap the edge 24 and partially contact the centralportion 30 of the lid.

The leading edge of the strip 16 may be defined as any portion of thestrip edge facing in a direction at least partially opposite to thedirection in which the strip 16 is pulled, represented by an arrow P inFIG. 2, and extending transversely to this direction. Ideally, the area46 should be near a portion of the edge which is perpendicular to thedirection P. While, with the rounded edge 24, the preferable position ofthe area 46 is symmetrical with respect thereto, the area can be locatedto one side or the other of this position, as indicated by the dottedareas designated 46. Whether the edge 24 is arcuate, triangular, square,or whatever, the area 46 will be satisfactorily positioned if theportion of the edge to which it is the closest is a leading edge asdefined above. As noted in FIG. 4, even the extreme two dotted areas 46are adjacent leading edge portions facing partially away from thedirection P and transversely to this direction.

With this positioning, whenever the tab 32 is raised, a relativelyconcentrated force will be applied to that part of the score linerepresenting the edge 24 adjacent the area 46 or 46 and thus initiateseparation of the score line at a very small portion thereof. Incontrast, with the integral rivet type of tab connection heretoforeemployed, the rivet had to be located at the center of the edge 24 inorder not to rupture or separate the score line as the rivet projectionwas being formed. consequently, when the tab was subsequently lifted,substantially the entire leading adge 24 around the periphery separatedat once with a definite popping sound and with considerable force beingrequired. The large initial force also was needed because the partingwas accomplished under tension rather than shear. By separating only asmall portion of the score line at a time by shearing, the forcerequired to initiate the opening of the lid is a fraction of the forceheretofore required.

Apparatus for Welding the tabs to the lids is shown in FIGS. 7 and 8. Inthis instance, the lids are supported and aligned by a guide 48 beneatha welding tool 50 which is moved toward and away from the lids 10 by ahydraulic cylinder 52. The cylinder 52 is of the double-acting type,moving the tool 50 toward the lid 10 when fluid is supplied underpressure to an upper line 54, and moving the tool away from the lid whenfluid under pressure is supplied to a lower line 56. As schematicallyshown in FIG. 7, the fluid can be supplied from a reservoir 58 through apump 60 to one of the lines 54 and 56 by an electrically controlledfour-Way valve 62. When fluid is supplied through one of the lines, itis returned through the other of the lines to the reservoir 58. In thisinstance, when the valve 62 is not energized, the fluid under pressuresupplied to the line 56 so as to position the tool 50 above the lid tobe Welded.

The tool 50 includes a magnetic chuck 64 consisting of a plurality ofconcentric rings 66 and 68 as shown in FIG. 9 with the lower surface ofthe chuck having a recess 70 of a contour to receive the tab 32. The tabcan be quickly assembled with the chuck 64 by being slipped into therecess 70 with the tapered end forward. In this manner, the tabs can bewelded at a relatively high rate of speed because of the quick loadingmade possible by the magnetic chuck. After the tab is welded to the lid,and the tool 50 is raised, the tab is automatically separated from thechuck 64, the lid and affixed tab being held down by a suitableelectrical contact 65.

The chuck 64 is affixed to a connecting leg 72 which is electricallyconnected to a cable clamp 74 to which a welding cable 76 is affixed.The cable clamp 74 is connected to a movable core 78 which extends intoa lifting coil 80. When the coil 80 is energized, it pulls in the core78 against a stop 82, and when the coil is de-energized, a plunge spring84 moves the clamp 74 downwardly until the tab 32 engages the lid 10,with the welding arc preferably applied between the tab and the lidduring the plunge stroke. The welding current establishes a molten poolof metal at the extremity of the dimple 44 and at the closest portion ofthe lid 10 with which the molten metal joining the two pieces when theyare placed in contact under pressure at the end of the plunge stroke.

The operation of the tool 50 and the ram 52 can be controlled with thecircuitry shown in FIG. 10. Accordingly, a source of'direct current isestablished between leads 86 and 88. When a manually-controlledoperating trigger 90 is closed, power is supplied to a coil 92 of thefour-way valve 62 to cause the cylinder 52 to move the tool 50downwardly until the tab carried by the chuck 64 moves into contact withthe lid 10; specifically, the dimple 44 engages the inwardly-extendingportion 22 of the strip. When this occurs, a circuit is establishedthrough a control relay 94. This causes normally-open contacts 94-1 toclose and complete a circuit through the lifting coil 80, therebyretracting the tab from the lid. The relay 94 can be held in during thewelding cycle by a capacitor 95, positioned thereacross. At the sametime, a pilot arc is established between the tab dimple and the lid bythe closing of normally-open contacts 942 which establishes a circuitthrough a resistance 96 across a main capacitor 98.

The control relay 94 has a third set of normally-open contacts 94-3located in series with a contactor 100 which is energized when thecontacts 94-3 are closed. The contactor 100 then closes heavy contacts100-1 thereby to establish a main welding are through an impedance 102and across the tab and lid to form the molten pools of metal thereon.This are is established by the capacitor 98, which are is of shortduration and effects a weld without destroying any protective coating onthe underside of the lid. At approximately the time the main welding arcis established, contacts 100-2 in series with the coil 80 opentode-energize the coil 80 and enable the plunge spring 84 to move the tabtoward the lid and complete the weld. The relay 94 is subsequentlyde-energized, when the trigger 90 is released and the capacitor isdischarged, to open its corresponding contacts, deenergize the contactor100, and return the welding circuitry to its original condition. At thistime, the capacitor 98 is recharged to a predetermined voltage by avoltage regulation circuit designated VR, as discussed more fully inGloroiso Patent 3,136,880, for example.

When the trigger 90 is released, the tool 50 is raised and the tabseparates from the magnetic chuck 64, remaining with the lid 10. A newtab can then be inserted quickly into the recess 70 of the chuck 64 anda new lid positioned therebelow. An extremely rapid attaching operationis thereby effected which can be made even faster by the use of suitableautomated feeding devices.

From the above, it will be appreciated that a fast and inexpensivemethod has been achieved by the use of the invention for attachingopening tabs to can lids. The particular attachment of the tab requiresno special metals and also enables the lid to be opened much more easilythan heretofore.

Various modifications of the above described embodiment of the inventionwill be apparent to those skilled in the art, and it is to be understoodthat such modifications can be made without departing from the scope ofthe appended claims.

I claim:

1. An opening tab to be attached to a scored opening strip of a can lid,said tab comprising a sheet of thin metal having a thickness of 0.012inch to 0.015 inch, said sheet having a pair of straight side edges anda tapered end tapering to a short edge having a length substantially notgreater than the width of the corresponding scored strip of the cam lid,said sheet having a projection extending from one side thereof adistance of from one thirty-second inch to one-fourth inch, saidprojection having a radius of curvature from three thirty-seconds inchto one-fourth inch, said projection being at said tapered end near saidshort edge, and said sheet having reinforcing ridges longitudinallyalong said side edges and extending at least to positions transverse toa portion of said projection.

2. An opening tab to be attached to a scored opening strip of a can lid,said tab comprising a sheet of metal having a pair of straight sideedges and a tapered end tapering to a straight short edge having alength substantially not greater than the width of the correspondingscored strip of the can lid, said sheet having a projection extendingfrom one side thereof adjacent said tapered end with the periphery ofsaid projection near said short edge, and said sheet having reinforcingridges longitudinally along said side edges and extending at least topositions transverse to a portion of said projection.

3. An elongate opening tab to be attached to a scored opening strip of acan lid, said tab comprising metal having a projection extendingtherefrom a distance of from one thirty-second inch to one-fourth inch,said projection having a radius of curvature from three thirty-secondinch to one-fourth inch, said projection being adjacent one end of saidtab.

4. An elongate opening tab of metal to be attached to a scored openingstrip of a can lid, said taib having a projection near one end andhaving a radius of curvature from three thirty-seconds inch toone-fourth inch.

5. In combination, a can lid having a scored spiral strip thereonextending around the periphery and inwardly toward a central portion ofthe lid and defining a spiral strip terminating in a rounded leadingedge portion at the inner end; an opening tab comprising a sheet ofmetal having a thickness of 0.012 to 0.015 inch, said sheet having apair of side edges, and a tapered end tapering to a straight short edgehaving a length substantially not greater than the width of said strip.at the inner end, said tab having reinforcing ridges extendinglongitudinally thereof along said side edges, said tab having aprojection extending from one side thereof a distance of from onethirtysecond inch to one-fourth inch, said projection having a radius offrom three thirty-seconds inch to one-fourth inch, said projection beingat said tapered end with the periphery of said projection spaced fromsaid short edge, said projection being affixed to said strip in aneccentric position close to said leading edge.

6. In combination, a can lid having a scored spiral strip thereonextending around the periphery and inwardly toward a central portion ofthe lid and defining a spiral strip terminating in a rounded leadingedge at the inner end; an opening tab comprising a sheet of metal havinga tapered end tapering to a short edge having a length substantially notgreater than the width of the inner end portion of said scored strip,said tab having reinforcing ridges extending longitudinally thereof,said tab having a projection extending from one side thereof adjacentsaid tapered end, said projection being afiixed to said strip at aposition close to a portion of said leading edge whereby only a smallportion of said edge will begin to separate when said tab is initiallypulled away from said lid.

7. In combination, a can lid having a scored spiral strip thereonextending around the periphery and inwardly toward a central portion ofthe lid and defining a spiral strip terminating in a rounded leadingedge portion at the inner end; an opening tab of metal having aprojection extending therefrom a distance of from one thirty-second inchto one-fourth inch, said projection having a radius of from threethirty-seconds inch to one-fourth inch, said projection being fixed tosaid leading edge portion.

8. In combination, a can lid having a scored spiral strip thereonextending around the periphery and inwardly toward a central portion ofthe lid and defining a spiral strip terminating in a leading edge at theinner end; an opening tab of metal having a projection extendingtherefrom near one end, said projection being affixed to said inner endat an off-center position close to a portion of said leading edgewhereby only a small portion of said edge will begin to separate whensaid tab is initially pulled away from said lid.

No references cited.

THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.

1. AN OPENING TAB TO BE ATTACHED TO A SCORED OPENING STRIP OF A CAN LID,SAID TAB COMPRISING A SHEET OF THIN METAL HAVING A THICKNESS OF 0.012INCH TO 0.015 INCH, SAID SHEET HAVING A PAIR OF STRAIGHT SIDE EDGES ANDA TAPERED END TAPERING TO A SHORT EDGE HAVING A LENGTH SUBSTANTIALLY NOTGREATER THAN THE WIDTH OF THE CORRESPONDING SCORED STRIP OF THE CAM LID,SAID SHEET HAVING A PROJECTION EXTENDING FROM ONE SIDE THEREOF ADISTANCE OF FROM ONE THIRTY-SECOND INCH TO ONE-FOURTH INCH, SAIDPROJECTION HAVING A RADIUS OF CURVATURE FROM THREE THIRTY-SECONDS INCHTO ONE-FOURTH INCH, SAID PROJECTION BEING AT SAID TAPERED END NEAR SAIDSHORT EDGE, AND SAID SHEET HAVING REINFORCING RIDGES LONGITUDINALLYALONG SAID SIDE EDGES AND EXTENDING AT LEAST TO POSITIONS TRANSVERSE TOA PORTION OF SAID PROJECTION.